The invention relates to an assembly comprising a turbine engine and an attachment system for attaching the turbine engine to an aircraft structure, and the invention relates more particularly to a rear covering providing a streamlined fairing for a mast and rear attachments forming part of the attachment system.
A bypass turbine engine presents an annular flow passage for the core stream coming from a gas generator and opening out at the rear around a central body, and an annular flow passage for the bypass stream coming from a fan and defined by a primary cover structure and a secondary cover structure.
Such a turbine engine is commonly attached to an aircraft structure, in particular a wing, by means of a mast, also referred to as a jet mast or a pylon, together with front and rear attachments connecting the mast to attachment points at the front and the rear of the engine, thrust-takeup links also being provided for transmitting thrust forces between the engine and the mast. Other attachment and thrust transmission devices connect the mast to the aircraft structure carrying the engine.
At the rear, a rear covering is provided for forming a streamlined fairing that protects the mast from the core stream and that covers the rear attachment.
The rear covering has two side walls that extend along and in the proximity of the mast on either side thereof and that extend rearwards beyond the rear opening of the core stream flow passage. At the front, the rear covering is arranged between the primary and secondary cover structures or at the outlet from the annular flow passage for the bypass stream. At least in its rear portion that is exposed on the inside to the core stream, the rear covering is provided with a soleplate or floor for providing thermal protection and for connecting together its side walls.
In the engines commonly in use at present, such as turbine engines of the “CFM 56” type from the supplier CFM International, the angular spacing between the rear attachment points of the engine is small enough for the streamlined fairing that is adapted to the mast also to cover the rear attachments and attachment points.
Improving the performance of turbine engines leads to envisaging a significant increase in their dimensions, and in particular in their diameter. This increase in diameter, and the resulting increase in weight, requires rear anchor points to be installed in such a manner that the distance between them becomes substantially greater than the width of the mast in the vicinity of the rear attachments.
There then arises a problem of providing a rear covering that serves to provide the mast and the rear attachment with a streamlined fairing and that gives rise to head losses that are as small as possible in order to avoid significantly affecting the specific fuel consumption (SFC) of the engine.